Allow 'h' and 'k' flags to be combined for mb_convert_kana

[alexdowad]

The 'h' flag makes mb_convert_kana convert zenkaku hiragana to hankaku katakana; 'k' makes it convert zenkaku katakana to hankaku katakana.

When working on the implementation of mb_convert_kana, I added some additional checks to catch combinations of flags which do not make sense; but there is no conflict between 'h' and 'k' (they control conversions for two disjoint ranges of codepoints) and this combination should not have been restricted.

Thanks to the GitHub user 'akira345' for reporting this problem.

Closes GH-10174.

FYA @cmb69 @youkidearitai

[youkidearitai]

Looks good to me.

[nikic]

I'd suggest to also add a positive test for the flag combination.

[alexdowad]

@nikic Nice to see you are still around!

[alexdowad]

Have just added the test case from GH-10174. Looks good?

[cmb69]

Looks good to me. Thank you!

[alexdowad]

Thanks, all. Merged.

[cjayalmontecm]

Hello @alexdowad @cmb69 , I encountered this issue Fatal error: Uncaught ValueError: mb_convert_kana(): Argument #2 ($mode) must not combine 'H' and 'K' flags , it is working on the previous version but not on PHP 8.2 . May I know if this expected result on 8.2?

[youkidearitai]

Yes, this is expected behavior. Combination of H and K is impossible.

H is 「半角カタカナ」(half-width katakana) to 「全角カタカナ」(full-width katakana).
K is 「半角カタカナ」(half-width katakana) to 「全角ひらがな」(full-width hiragana).

[alexdowad]

Thanks so much, @youkidearitai.
Indeed, it is impossible for mb_convert_kana to obey both the H and K directives at the same time. In older versions, some such conflicts were quietly ignored (one of the conflicting directives would override the other). Now an error is raised to alert the programmer.